Endoscopic and other minimally invasive surgical instruments typically include an end effector positioned at the distal end of an elongate shaft and a handle at the proximal end of the elongate shaft allowing a clinician to manipulate the end effector. In use, the end effector is provided to a surgical site through a cannula of a trocar. At the surgical site, the end effector engages tissue in any number of ways to achieve a diagnostic or therapeutic effect. Endoscopic surgical instruments are often preferred over traditional open surgical instruments because they require smaller incisions that generally heal with less post-operative recovery time than traditional open surgery incisions. Because of this and other benefits of endoscopic surgery, significant development has gone into a range of endoscopic surgical instruments having end effectors that engage tissue to accomplish a number of surgical tasks. For example, end effectors have been developed to act as endocutters, graspers, cutters, staplers, clip appliers, access devices, drug/gene therapy delivery devices, ultrasound, RF, or laser energy devices, and other surgical instruments.
FIGS. 1 & 2 show an exemplary prior art surgical and stapling instrument 10 including an end effector 12 configured as an endocutter for clamping, severing and stapling tissue, for example, as disclosed in U.S. Application Publication No. 2004/0232196 A1, the disclosure of which is herein incorporated by reference in its entirety. The surgical stapling and severing instrument 10 includes a handle portion 20 connected to an implement portion 22, the latter further comprising a shaft 23 distally terminating in the end effector 12. The handle portion 20 includes a pistol grip 24 toward which a closure trigger 26 is pivotally drawn by the clinician to cause clamping, or closing, of the anvil 18 toward the elongate channel 16 of the end effector 12. A firing trigger 28 is farther outboard of the closure trigger 26 and is pivotally drawn by the clinician to cause the stapling and severing of clamped tissue in the end effector 12.
Closure trigger 26 is actuated first. Once the clinician is satisfied with the positioning of the end effector 12, the clinician may draw back the closure trigger 26 to its fully closed, locked position proximate to the pistol grip 24. Then, the firing trigger 28 is actuated. The firing trigger 28 springedly returns when the clinician removes pressure. A release button 30 when depressed on the proximal end of the handle portion 20 releases any locked closure trigger 26.
A closure sleeve 32 encloses a frame 34, which in turn encloses a firing drive member 36 that is positioned by the firing trigger 28. The frame 34 connects the handle portion 20 to the end effector 12. With the closure sleeve 32 withdrawn proximally by the closure trigger 26 as depicted, the anvil 18 opens, pivoting away from the elongate channel 16 and translating proximally with the closure sleeve 32. The elongate channel 16 receives a staple cartridge 37.
With particular reference to FIG. 2, the firing bar 14 includes three vertically spaced pins that control the spacing of the end effector 12 during firing. In particular, an upper pin 38 is staged to enter an anvil pocket 40 near the pivot between the anvil 18 and elongate channel 16. When fired with the anvil 18 closed, the upper pin 38 advances distally within a longitudinal anvil slot 42 extending distally through anvil 18. Any minor upward deflection in the anvil 18 is overcome by a downward force imparted by the upper pin 38.
Firing bar 14 also includes a lower most pin, or firing bar cap, 44 that upwardly engages a channel slot 45 in the elongate channel 16, thereby cooperating with the upper pin 38 to draw the anvil 18 and the elongate channel 16 slightly closer together in the event of excess tissue clamped therebetween.
The firing bar 14 advantageously includes a middle pin 46 that passes through a firing drive slot 47 formed in a lower surface of the cartridge 37 and an upward surface of the elongate channel 16, thereby driving the staples therein as described below. The middle pin 46, by sliding against the lower surface of the cartridge 37, advantageously resists any tendency for the end effector 12 to be pinched shut at its distal end.
A distally presented cutting edge 48 between the upper and middle pins 38, 46 on the firing bar 14 traverses through the cartridge 37 to sever clamped tissue. The affirmative positioning of the firing bar 14 with regard to the elongate channel 16 and anvil 18 assure that an effective cut is performed.
The affirmative vertical spacing provided by the E-Beam firing bar 14 is suitable for the limited size available for endoscopic devices. Moreover, the E-Beam firing bar 14 enables fabrication of an anvil 18 with a camber imparting a vertical deflection at its distal end. This cambered anvil 18 advantageously assists in achieving the desired gap in the end effector 12 even with an anvil 18 of reduced thickness, which is thus more suited to the size limitations of an endoscopic device.
The E-Beam firing bar 14 further enables increased applications, especially in combination with a range of configurations of staple cartridges. For instance, a clinician may select a gray staple cartridge yielding a 0.02 mm tissue gap, a white staple cartridge yielding a 0.04 mm tissue gap, a blue cartridge yielding a 0.06 mm tissue gap, or a green cartridge yielding a 0.10 mm tissue gap. The vertical height of each respective staple cartridge in combination with the length of staples and an integral wedge sled 50 predetermines this desired tissue thickness with the anvil 18 appropriately vertically spaced by the E-Beam firing bar 14.
With surgical instrument 10 as well as other minimally invasive instruments, the positioning of the end effector at the surgical site is constrained by the trocar. Generally the elongate shaft 23 enables the clinician to insert the end effector to a desired depth and rotate the end effector about the longitudinal axis of the shaft. This allows the end effector to be positioned at the surgical site, to a degree. With judicious placement of the trocar and use of graspers, for instance, through another trocar, this amount of positioning is often sufficient. Depending upon the nature of the operation, however, it may be desirable to adjust the positioning of the end effector of an endoscopic surgical instrument. In particular, it is often desirable to orient the end effector at any one of multiple angles relative to the longitudinal axis of the elongate shaft of the instrument.
Movement of the end effector through multiple angles relative to the instrument shaft is conventionally referred to as “articulation.” Articulation is typically accomplished by a pivot (or articulation) joint being placed in the elongate shaft just proximal to the end effector. This allows the clinician to articulate the end effector remotely to either side for better surgical placement of the staple lines and easier tissue manipulation and orientation. An articulating end effector permits the clinician to more easily engage tissue in some instances, such as behind an organ. In addition, articulated positioning advantageously allows an endoscope to be positioned behind the end effector without being blocked by the elongate shaft.
Approaches to articulating end effectors tend to be complicated because mechanisms for controlling the articulation must be integrated with mechanisms for operating the end effector. For example the closure sleeve, drive member and mechanisms for articulation must be implemented within the small diameter constraints of the instrument's shaft. One common design involves an accordion-like articulation mechanism (“flex-neck”) that is articulated by selectively drawing back one of two connecting rods through the implement shaft, each rod offset respectively on opposite sides of the shaft centerline. The connecting rods ratchet through a series of discrete positions.
While this generally-known approach successfully articulates the end effector about an articulation pivot, it is desirable to further enhance performance. Consequently, a significant need exists for an improved articulating surgical instrument.